1. Field of Invention
The present invention relates to automatic or remotely operable pressure vessel units. The present invention is directed towards cokers having coke drums that are useful in hydrocarbon refineries; however, it can relate to closure devices and joint connectors for pipes, tanks and other various conduits where hazardous conditions exit, or, in situations where rapid opening and closing of a joint is desired.
The present invention, in part, comprises a remotely operable joint connector that is especially useful in cokers, where extremely high temperature and relatively high pressure exist. In particular this connector is especially suited for the deleterious effects of coke exposure or other "dirty" operations.
2. Background of the Invention
Coke drums are structures in hydrocarbon refineries, where, inside these coke drums, heat and moderate pressure turn hydrocarbon residuum into lighter products and a hard, coal-like substance--coke. A pair of coke drums cycle between coking and decoking. One coke drum is coking (joints connected and operating at about 975.degree. F.), while the other is decoking (quenching, followed by remotely opening the joints then decoking the drum). In the decoking phase coke is removed from the coke drums by high pressure hydrostatic drilling. A drill bit is lowered into the coke drum through a drum-top deheading system and coke, cut by the drilling action, falls through a decoke chute attached to an opening in the bottom of the coke drum created when a drum-bottom deheading system removes a closure away from said opening.
Safely preparing a coke drum for decoking involves the following steps: (1) removing the working surface opening cover creating an opening in the working surface for the coke to pass; (2) remotely aligning and engaging a closure transport to the drum-bottom closure; (3) remotely energizing the drum-bottom closure to the coke drum; (4) remotely unlocking, disconnecting and separating the coke drum from the inlet pipe; (5) remotely unlocking the drum-bottom closure from the coke drum; (6) remotely disengaging the drum-bottom closure from the coke drum in a controlled manner; (7) remotely removing the drum-bottom closure from the opening in the bottom of the coke drum; (8) remotely producing and securing a passageway between the bottom opening of the coke drum to the opening in the working surface, i.e. a decoke chute; (9) remotely unlocking and moving the drum-top closure from the opening in the top of the coke drum; (10) lowering the drill bit into the coke drum through the opening in the top of the coke drum; and (11) engaging and locking the drilling head to the drum-top deheading system.
Safely preparing a decoked coke drum for coking involves the following steps: (1) remotely replacing, aligning and locking the drum-top closure to the coke drum once the drill bit is removed from the coke drum; (2) remotely decommissioning the decoke chute and replacing the working surface opening cover; (3) remotely aligning and locking the open ends of the inlet piping together, which reconnects the coke drum to the inlet pipe; (4) remotely replacing, aligning and locking the drum-bottom closure to the opening at the bottom of the coke drum.
Currently most cokers employ workers to manually perform some or all of the foregoing steps. Any of these steps can be hazardous to workers, but by far the most dangerous steps are in the transition from the coking phase to the decoking phase. Here a closed and quenched coke drum must be opened to allow the evacuation of coke from the coke drum.
Workers are most frequently harmed while performing the following steps: (1) manually unlocking, disconnecting and separating the coke drum from the inlet pipe; (2) manually unlocking the drum-bottom closure from the coke drum; or (3) manually disengaging the drum-bottom closure from the coke drum.
Coke is supposed to support itself in the coke drum when an opening is created at the drum-bottom; however, this cannot be assured. The flow of loose coke and quench water or other materials from other types of vessels can be very hazardous for workers performing functions during the opening of the vessels. This hazard exists until a secure passageway is present between the opening of the vessel and where the material is ultimately destined. In the case of a coking unit, the material is due to fall in a hole in a working surface located beneath the unit and towards an ultimate destination below the working surface. An even more hazardous environment is a coker design to produce "shot coke" where the coke will not support itself in the coke drum.